The Iguanas of Gasparilla Island

by Scott Robert Ladd

It began with a gift.

On a semi-tropical Florida island, a grandfather gives two baby iguanas to his grandson. The lizards grow up in a cage in the back yard, never breeding. When the family moves away from the island, they let the iguanas loose in a park.

Twenty years later, two have become more than ten thousand.

In the winter of 2004, the iguanas were the topic of several meetings of Gasparilla Island residents, animal control officers, biologists, and other interested parties. Most of the reports I've read come from one of the local newspapers, the Boca Beacon, and the overall tone was one of frustration and anger. It seemed that many people wanted the iguanas gone, and were willing to do whatever was necessary to accomplish that goal.

In the following ten months, little actually happened. A few scientists have studied the animals, looking for a solution, and there is talk of more meetings. Some people in town are angry with the local paper for its articles; other people, I'm told, have taken matters into their own hands with iguanas they find on their property.

At the end of September 2005, I paid $4.00 to cross a small drawbridge onto Gasparilla Island. A quality two-lane road, flanked by a bike path, carries me south through palms. Everything is neatly manicured; I feel as if I'm entering a private estate.

The water, close by the road, is crystal clear and shallow; it smells of red tide. I'll later see dead fish on the beaches, killed by algae that has caused problems all along the Gulf Coast of Florida this year.

Geographically, the island is typical of its kind, a narrow sandy barrier 10.5 kilometers long, lying between Boca Bay and the Gulf of Mexico. Nearly every square inch of the island has been modified for human use, from a country club golf course to the lovely and compact town of Boca Grande. The entire island projects a sense of wealth in its manicured parkways and trophy homes. Downtown hosts a large community center, real estate agencies, tourist shops, and restaurants. The sounds of power tools and hammers echo everywhere I go.

The island is not entirely given over to human domination. Two small parks along the shore provide habitat and protection for shorebirds, sea turtles, and gopher tortoises. A short lighthouse on the southernmost tip of the island is a tourist attraction.

We spy our first iguana on a quiet street a block from the business district; it's a large rusty-headed animal, sitting on the ground near a parked car. I stop, the lizard looks over its shoulder at me and scurries under a nearby car.

Talking to people around town does little to clarify the situation. From real estate agents to yard workers to shopkeepers, the universal response to my questions is one of bemused annoyance at the iguanas. There's even a slight sense of fondness for the reptiles from some people. I saw no evidence of a campaign to eradicate the invaders, no sign of the fervor described in dozens of newspaper articles from last winter. Where has all the anti-iguana sentiment gone?

Perhaps the answer is given by vacant houses that line many streets, particularly toward the southern end of the island. Like many dormant businesses downtown, these empty homes wait for their owners to return from Canada or New York or Michigan. When the "snow birds" re-inhabit their winter refuges, they find iguanas in the attic, and the garden, and... well, I'm certain you get the picture.

Finding iguanas was my goal for this first trip. I wanted to see them in person, to get photographs, and to verify what I'd read about spiny iguanas in papers and scientific journals. The species, Ctenosaura similis, is native to Central and South America. These animals are slightly smaller than the typical Green Iguana kept as a pet by many people (including myself). When young, the spiny-tailed iguanas eat insects; upon reaching maturity, their diet shifts to plants, though they also eat eggs, fruit, flowers, and even other small animals.

Traveling south from town, I started seeing iguanas everywhere. Iguana heads poke out above the tall grass, like periscopes; they lie on picnic benches, sun in parking lots, and forage through the brush and grass. Their variety surprised me; the largest ones were four or five feet long, with tall spines along their backs. Tiny babies sported bright green bodies and brown tails; young adults and juveniles came in earth tones, sometimes adorned by orange-tan spots and black stripes. One large specimen had a brilliant pink throat and orange markings on its head. Pink-throat, like most of the iguanas, ran away as soon as my truck's door latch went click — but in a picnic area, I found a pair of young adults who seemed to appreciate being photographed.

Clearly, the iguanas are thriving in a place far from their "home." Why do some animals succeed while others struggle to survive? For example: Iguanas have established breeding populations in many parts of Florida, but the native kingsnake is nearing extinction in the wild. The same dichotomy exists everywhere; struggles to save indigenous species seemed doomed to failure, yet extirpating alien invaders appears to be a nigh-impossible task.

Many native species have small ranges and specific niches enforced by a complex web of ecological relationships. The invaders, however, show remarkable flexibility, adapting diets and behaviors to the available resources. And so it is that wolves were exterminated in much of the U.S. while their lanky coyote cousins continue expanding their territory; it is why a sea tortoise, needing a quiet beach, is struggling for survival, while the population of adaptable iguanas explodes.

I stopped by the state park office, and was greeted by Bud Amen, a wiry fellow who's lived on the island for decades. To my first question about the iguanas, he responds definitively.

"They're a nuisance," he said. "They're into my orchids, they're into my hibiscus, they're into my tomato plants, they're into everything. They'll get into your attic. They'll get into your house. And of course, my wife and I had them come up in the john. We had three of them do that until I figured out how they were doing it. They were going on the roof and coming down the vent stack." Bud also mentioned how the iguanas tear up fiberglass insulation for nesting material.

When I asked if the iguanas were eating shorebird eggs, Bud said: "I had a nest of doves in my shop, just above the door. I saw where one of the iguanas had gotten up there and got an egg, but dropped it on the floor. The doves disappeared after that."

Bud was one of the people who told me how the iguanas had all come from just two or three ancestors. It's not difficult to believe that two iguanas could become 10,000 in twenty years; a female spiny-tail can lay 20-80 eggs in a clutch, two or three times each year.

We discussed the lack of simple solutions. "The only thing we need is a good cold winter," he said. "We haven't had a cold winter here in a long, long time." Indeed, the Gulf is very, very warm, resulting in stronger hurricanes and milder winters. Whether it is due to human activities or natural cycles, one effect of global warming can be seen in thousands of iguanas living far north of their natural range.

I ask about other invasive species, and Bud casually mentions the presence of Green Iguanas on the island. He's seen two, one in town and another down on the coast along Boca Bay.

Just two — isn't that how it all began with their spiny-tailed cousins?

I returned home that evening to find a copy of Amphibians and Reptiles: Status and Conservation in Florida, a new collection of scientific papers about the state of "native" species. The invaders, for good or ill, have become the de facto natives in many places. Certainly the iguanas of Gasparilla Island are now part of the landscape, and they show no signs of leaving soon.

To be continued...

My next trip to the island (in early October) will include visits with more park employees and a better look at the town and its resident iguanas. I'm also arranging interviews with herpetologists who've studied the iguanas, and I want to talk to trappers and county animal control officers. Later in the year, I'll return when the "snow birds" have arrived for the winter, to see if and how attitudes change. I also want to take more pictures of the town and the surrounding areas.